Sensor for a Motor Grader

ABSTRACT

A motor grader may include a moldboard assembly movably connected to a main frame of the motor grader to move with respect to a plurality of dimensions. The moldboard assembly may include a blade having a lower cutting edge, an upper free edge, and first blade side, and a second blade side. The moldboard assembly may be adapted to pivot the blade by moving the upper free edge with respect to the lower cutting edge. The moldboard assembly may be adapted to change the cross-slope of the blade by moving the first blade side with respect to the second blade side. To determine the pitch and/or cross-slope, a blade sensor may be mounted to the moldboard assembly. The location of the blade sensor on the moldboard assembly may protect the blade sensor and allow the blade sensor to directly measure the pitch and/or cross-slope of the blade.

TECHNICAL FIELD

This patent disclosure relates generally to a sensor and method for sensing the position of a work implement on an earth moving machine and more particularly to sensing and controlling the position of a moldboard assembly that includes a blade on a motor grader.

BACKGROUND

Motor graders are a type of machine for moving earth and similar material about a worksite during the construction of a roadway, parking lot, airport runway or the like, and are particularly adapted for fine grading or final contouring of the material about the worksite. Motor graders typically include a frame supported on wheels for travel over the grounds of the worksite and further include a work implement in the form of a moldboard assembly having a blade supported by the frame to engage the ground. To enable the motor grader to perform fine grading and final surface contouring operations, the moldboard assembly and the blade are highly maneuverable and can be placed into a number of different positions with respect to the frame and the ground. For example, the moldboard assembly and blade may be swiveled or rotated from a position perpendicular to the direction of travel through various other angular orientations relative to the direction of travel so that materials engaged by the blade are directed or pushed off toward the side of the motor grader. In addition, the elevation of the blade can be adjusted with respect to the ground to change the amount of cut taken. Further, the angle of the blade traverse to the direction of travel can be adjusted to change the slope of the cut, allowing the operator to simultaneously forming the crown and a side shoulder of a roadway. The frame of the motor grader itself may be articulated to assist during turns and other systems, such as the suspension, may be movable to allow for further positioning of the blade with respect to the ground.

To assist the operator of the motor grader with accurate positioning of the moldboard assembly and blade, the motor grader may be operated with various sensors and controls. These components interact with each other and can be communicatively networked together through an electronic control unit, control system, or controller. One example of a controller and associated system for a motor grader is described in U.S. Pat. No. 10,030,366, issued on Jul. 24, 2018. The '366 patent describes a configuration of linkages, actuators, and structures for maneuvering the moldboard assembly and blade to various positions and further describes a network or array of sensors for determining the position of the moldboard and blade during operation. The present disclosure is similarly directed to an arrangement of position sensors on a motor grader to facilitate operation.

SUMMARY

The disclosure describes, in one aspect, a motor grader having a main frame defining a longitudinal axis and a moldboard generally traverse to the main frame. The moldboard assembly can include a blade having an upper free edge, a lower cutting edge, a first blade side, and a second blade side. The moldboard assembly is movably connected to the main frame to pivot the blade by moving the upper edge with respect to the cutting edge and to adjust the cross-slope of the blade by vertically moving the first blade side with respect to the second blade side. The motor grader may further include a blade sensor disposed on, and movable with, the moldboard assembly that is adapted to measure pitch of the blade and cross-slope of the blade.

In another aspect, the disclosure describes a motor grader, including a main frame, defining a longitudinal axis and a moldboard assembly movably connected to the mainframe. The moldboard assembly may be adapted to move with respect to the main frame in a first dimension associated with a vertical axis perpendicular to the longitudinal axis and to move with respect to the frame in a second dimension associated with a lateral axis traverse to the longitudinal axis. The motor grader may further include a blade sensor mounted to the moldboard assembly and adapted to directly measure movement of the moldboard assembly in the first dimension and in the second dimension.

In yet another aspect, the disclosure describes a control system for controlling operation of a motor grader. The motor grader may include a drawbar-moldboard-circle assembly including a drawbar movably connected to a frame of the motor grader, a circle assembly rotatably connected to the drawbar, and a moldboard assembly pivotally connected to the circle assembly. A blade sensor may be disposed on a moldboard assembly of the motor grader and may be configured to measure pitch and cross-slope of the moldboard assembly. A controller can be in communication with the blade sensor to receive from the blade sensor a first signal indicative of pitch of the moldboard and a second signal indicative of the cross-slope of the moldboard assembly. The controller may be further configured to process the first signal and the second signal to generate one or more control signals to control positioning of the moldboard assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an exemplary motor grader configured with a blade sensor for determining the position of the moldboard assembly and blade in accordance with the disclosure.

FIG. 2 is an isometric view of the rear of a drawbar-moldboard-circle assembly movably connected to the main frame of the motor grader.

FIG. 3 is a representative diagram of the drawbar-moldboard-circle assembly that illustrates possible movements and orientations of the moldboard assembly that the blade sensor can be measure.

FIG. 4 is an isometric view of the blade sensor disposed on the moldboard assembly and accommodated in a protective cover.

FIG. 5 is a flowchart representing a possible process for utilizing the measurements made by the blade senor to adjust the position of the moldboard assembly.

DETAILED DESCRIPTION

Now referring to the figures, wherein like reference numbers refer to like elements, there is illustrated in FIG. 1 an exemplary machine for moving or displacing earthen materials or construction aggregates about a worksite in the exemplary form of a motor grader 100. Motor graders 100 are employed primarily as finishing tools for forming fine contours or shaping the finished surface of the worksite by moving relatively small quantities of material toward either side of the motor grader 100. To displace the material, the motor grader 100 may have a work implement in the form of a moldboard assembly 102 which is suspended from the motor grader 100 to contact and engage the surface or ground 104 at the worksite. However, while the present disclosure is described with respect to a motor grader 100, aspects of the disclosure may be applicable to other earth moving machines such as bulldozers, loaders, excavators, scrapers and the like. In addition, in other embodiments, the machines may include other work implements instead of or in addition to the moldboard assembly 102.

To support the moldboard assembly 102 or other work implement, the motor grader 100 includes a main frame 110 that may be relatively elongated and oriented to define the longitudinal axis 112 (indicated by an arrow), which may correspond to the forward and/or rearward travel directions normally undertaken by the motor grader 100 in operation when not turning. For reference purposes, the main frame 110 may also delineate the left and right lateral sides of the motor grader 100, which may define a lateral axis 114 horizontal or coplanar to the ground 104 and perpendicular to the longitudinal axis 112. The lateral axis 114 traverses the main frame 110 and is viewed as a dot projecting into the plane of FIG. 1. For further reference, the motor grader 100 may be associated with a vertical axis 116 perpendicular to the longitudinal axis 112 and the lateral axis 114 and to the ground 104. The longitudinal axis 112, lateral axis 114, and vertical axis 116 may be arranged as a Cartesian coordinate system with corresponding x-y-z axes. All reference to the axes and dimensions of the motor grader 100, however, are for reference purposes only and should not be consider a limitation on the scope of the claims.

In the illustrated embodiment, the main frame 110 may be further configured as a two-part articulated frame having a rear frame portion 120 and a front frame portion 122 that are joined at an articulated joint 124 approximately at the midpoint along the length of the motor grader 100. The rear frame portion 120 and front frame portion 122 may be manufactured from structural beams of carbon steel or similar high strength material. The articulated joint 124 enables the front frame portion 122 to pivot with respect to the rear frame portion 120, for example, to assist in turning the motor grader 100 when changing the travel direction associated with the longitudinal axis 112 or for performing special or unique tasks such as operating the motor grader 100 in a “crabbed” configuration in which the rear frame portion 120 and the front frame portion 122 are not inline with each other. To enable the motor grader 100 to move or travel with respect to the ground 104, the rear frame portion 120 is supported on a plurality of driven traction devices such as drive wheels 126 and the front frame portion 122 is supported on a plurality of steerable traction devices such as steerable wheels 128 on either lateral side of the motor grader 100 which can be used to turn and steer the motor grader 100. However, in other embodiments, other forms of traction devices such as continuous tracks may be employed.

To cause the drive wheels 126 to rotate, the motor grader 100 includes an internal combustion engine 130 accommodated on the rear frame portion 120 that connects to the drive wheels 126 through a drivetrain. The drivetrain includes a transmission or other components for assisting and adjusting the transfer of mechanical power. The internal combustion engine 130 can be any suitable type of engine including, for example, a diesel engine, a spark ignition gasoline engine, a natural gas engine or any other engine known in the art. In other embodiments, the power source may be a non-combustive source of power such as a fuel cell, power storage device or other electrical source. In addition to powering the drive wheels 126, the internal combustion engine 130 or other power source can be operatively associated with a hydraulic system 132 that may supply pressurized hydraulic fluid to various hydraulic actuators and components disposed about the motor grader 100 to assist in its operation and maneuverability.

To accommodate the operator of the motor grader 100, an operator's station (or cab) 134 is mounted on the rear frame portion 120. The operator's cab 134 accommodates the controls and instruments necessary to control operation of the motor grader 100 that may include one or more input devices 136. The input devices 136 may be in the form of a hand lever or joystick that the operator may manipulate to steer the motor grader 100 and selectively adjust the position and orientation of the moldboard assembly 102 with respect to the ground 104. Other input devices 136 may include steering wheels or the like. In addition to the input devices 136, the operator's cab 134 may include one or more display devices 138, such as a digital or touchscreen LCD or CRT display screen or the like, to interface with the operator. As can be appreciated, the display devices 138 can interface with the operator to provide information regarding the subsystems of the motor grader 100 during operation including for example, the position of the moldboard assembly 102.

Additionally, the input devices 136 and the display devices 138 can be operatively associated with an onboard electronic control unit, control system or controller 139. The controller 139 can be adapted to assist in operation of the motor grader 100 by monitoring various operating parameters and responsively regulating various functions affecting operation of the motor grader 100. The controller 139 may include a microprocessor, an application specific integrated circuit (ASIC), or other appropriate circuitry and may have memory or other data storage capabilities. The controller 139 may include functions, steps, routines, data tables, data maps, charts and the like saved in and executable from read-only memory or another electronically accessible storage medium to assist in operation of the motor grader 100. Although in FIG. 1, the controller 139 is illustrated as a single, discrete unit, in other embodiments, the controller 139 and its functions may be distributed among a plurality of distinct and separate components. To receive operating parameters and send control commands or instructions, the controller 139 may be operatively associated with and may communicate with various sensors and controls disposed about the motor grader 100, including those sensors described herein. Communication between the controller 139 and the sensors may be established by sending and receiving digital or analog signals across electronic communication lines or communication busses.

Referring to FIGS. 1 and 2, to support and selectively position the moldboard assembly 102 when conducting various grading operations, the moldboard assembly 102 can be operatively associated with a drawbar-circle-moldboard (DCM) assembly 140 that is disposed generally under the front frame portion 122. As familiar to those of skill in the art, the DCM assembly 140 can include a drawbar 142 that may be an A-frame truss-like structure that is connected to the foremost structure of the front frame portion 122 with a multidimensional universal joint 144 such as a ball-and-socket joint. The drawbar 142 extends generally rearward from the universal joint 144 to a distal end 146 and may be generally supported horizontally above the ground 104. Disposed toward the distal end 146 of the drawbar 142 is a circle assembly 150 configured to rotate or swivel the moldboard assembly 102 with respect to a rotational axis line 152. The rotational axis line 152 of the circle assembly 150 may be generally parallel to the vertical axis 116 of the motor grader 100 and oriented generally perpendicularly with respect to the ground 104.

The circle assembly 150 can include an outer circle 154, which may be an annular structural bar of forged steel or the like disposed around and circumscribing a correspondingly shaped internal journal disk 156. The journal disk 156 may be fixedly mounted or joined to the underside of the drawbar 142 such that the journal disk 156 is also horizontally supported above the ground 104. The circle 154 and the journal disk 156 may interface at their respective internal and external peripheries via bearings and tracks so that the journal disk 156 is journalled inside the circle 154 which can rotate or swivel with respect to the rotational axis line 152 to rotate the moldboard assembly 102 with respect to the drawbar 142.

The moldboard assembly 102 can be depended from and be disposed below the circle assembly 150 and can be attached to the circle 154 by connecting arms 158. The connecting arms 158 can be attached to opposite sides of the outer circumference of the circle 154 and can be generally arcuate in shape to descend toward the ground 104. To physically engage the ground 104, the moldboard assembly 102 can include a blade unit 160 that accommodates and supports an elongated blade 162. The blade 162 is made of formed and finished steel or other high-strength material. The blade 162 extends between the opposite lateral sides of the motor grader 100 and generally traverses the longitudinal axis 112 established by the main frame 110. To facilitate displacement of material cut or removed from the ground 104, the blade 162 can have a curved front face 164 that curves from a lower cutting edge 166 to an upper free edge 168. The curved front face 164 may be generally oriented forward in the direction of travel along the longitudinal axis 112 to encounter material on the ground 104. Moreover, the elongated blade 162 may have a first blade side 170 and a spaced apart second blade side 172 that defines a blade length 176, with the first and second blade sides 170, 172 typically disposed toward the respective left and right lateral sides of the motor grader 100 established by the lateral axis 114. The blade 162 therefore may have an overall rectangular shape with its midpoint position 178 located mid length between the first and second blade sides 170, 172 and mid height between the lower cutting edge 166 and upper free edge 168. Because of the curved front face 164, however, the first and second blade sides 170, 172 likewise have a curved or arcuate shape. In an embodiment, teeth or bits may be disposed on the lower cutting edge 166 of the blade 162.

To operatively connect to the moldboard assembly 102 with the connecting arms 158 descending from the circle assembly 150, the blade unit 160 can include a rear support bracket 180 disposed along the rear of the blade 162 opposite the curved front face 164. The rear support bracket 180 may have an elongated configuration similar to the blade 162 and may function to support the blade 162 when engaging the ground 104. The distal ends of the connecting arms 158 may connect to the lower edge of the rear support bracket 180, proximate to the lower cutting edge 166 of the blade 162, by pivot joints 182 to enable hinged or pivotal movement of the moldboard assembly 102 as described further herein. The rear support bracket 180 may also include one or more channels, guides, or rails 184 that allow the blade 162 to translate or slide with respect to the lateral axis 114, thereby increasing the lateral reach of the blade 162 toward the sides of the motor grader 100.

Continuing with reference to FIGS. 1 and 2, to adjust the position or orientation of the moldboard assembly 102 during cutting and grading operations, the motor grader 100 can include a plurality of actuators such as hydraulic cylinders in fluid communication with the hydraulic system 132. The hydraulic actuators are operatively associated with hydraulic control valves to selectively direct fluid to and from the hydraulic actuators causing actuation such as, in the example of a cylinder, extension or retraction of the cylinder arm. For example, to raise and lower the moldboard assembly 102 with respect to the ground 104, the motor grader 100 can include hydraulically extendable and retractable actuators and such as a first lift cylinder 190 and a second lift cylinder 192. The first and second lift cylinders 190, 192 can be arranged in a pair with one each disposed to either lateral side of the front frame portion 122 of the motor grader 100. The first and second lift cylinders 190, 192 can be arranged vertically, generally parallel with respect to the vertical axis 116 and, accordingly, to the rotational axis line 152. The first and second lift cylinders 190, 192 are operatively coupled to the DCM assembly 140, for example by universal pin joints 194 disposed on top of the journal disk 156 of the circle assembly 150. Simultaneous actuation of the first and second lift cylinders 190, 192 can vertically move the DCM assembly 140 with respect to the universal joint 144 connecting the drawbar 142 to the front frame portion 122.

Other actuators may include a side shift actuator 200 that connects to the DCM assembly 140 proximate the rear of the journal disk 156 to laterally swing the DCM assembly 140 about the universal joint 144 toward the lateral sides of the motor grader 100. To laterally extend the blade 162 toward either side of the motor grader 100, a blade extension cylinder 202 can be accommodated on the rear support bracket 180 and can be operatively connected to the blade 162 to move the blade 162 via the channels, guides and rails 184. In an embodiment, the blade extension cylinder 202 may be laterally disposed along a portion of the blade length 176 between the first and second connecting arms 158. To pivot the moldboard assembly 102 forward and backwards with respect to the pivot joints 182 joining the rear support bracket 180 to the connecting arms 158, a pitch cylinder 204 can be included. In the illustrated embodiment, the pitch cylinder 204 may be connected between a circle post 206 projecting rearwardly from the circle 154 and the top of the rear support bracket 180 to be proximate to the upper free edge 168 of the blade 162, for example, to a bracket post 208 projecting from the rear support bracket 180. As previously indicated, the circle assembly 150 may include a drive mechanism to rotate the circle 154 about the journal disk 156 with respect to the rotational axis line 152.

The foregoing arrangement enables movement and positioning of the moldboard assembly 102 in multiple degrees of freedom with respect to the longitudinal axis 112, lateral axis 114, and vertical axis 116, for different grading operations. Referring to FIGS. 2 and 3, and as indicated above, simultaneously extending or retracting the first and second lift cylinders 190, 192 raises and lowers the vertical elevation of the moldboard assembly 102 with respect to the vertical axis 116 to control the depth of cut of the blade 162 into the ground 104 or the thickness of material being dispersed. Furthermore, the first and second lift cylinders 190, 192 may be independently extendable and retractable to vertically move the corresponding first and second blade sides 170, 172 with respect to the vertical axis 116 and relative to each other and to the ground 104. Vertically moving the first and second blade sides 170, 172 relative to each other adjusts the cross-slope of the cut made by the blade 162 with respect to the ground 104. The adjusted blade 162 position is indicated in dashed lines in FIG. 3, with the cross-slope indicated by CS. Altering the cross-slope cause the vertical height of the ground 104 to change along the lateral direction associated with the lateral axis 114 and traverse to longitudinal axis 112 of the motor grader 100 when, for example, forming the crown and/or side shoulder of the roadway.

To adjust the angle of the blade 162 with respect to the longitudinal axis 112 in the direction of travel, the circle assembly 150 can be rotated with respect to the rotational axis line 152, as indicated by arrow RR, thereby swiveling the moldboard assembly 102. Swiveling switches from directing material straight ahead when the moldboard assembly 102 is at 0° angle (perpendicular to the longitudinal axis 112) to directing material laterally to the sides of the motor grader 100 when the moldboard assembly 102 is at some non-perpendicular angle with respect to the longitudinal axis 112. To pivot the moldboard assembly 102, the pitch cylinder 204 can be extended or retracted to move the upper free edge 168 of the blade 162 ahead of or behind the cutting edge 166, as indicated by arrow P. Pivoting the moldboard assembly 102 rotates the curved front face 164 of the blade 162 and thereby adjusts the angle of cut made by the lower cutting edge 166 into the ground 104. Adjusting the pitch of the moldboard assembly 102 may also determine the amount of material the motor grader 100 can remove from the ground 104.

To assist in adjusting and positioning the moldboard assembly 102 with respect to the main frame 110 and the ground 104, the motor grader 100 may include various sensors and measurement units. For example, a blade sensor 210 can be disposed on the blade unit 160 at a location to enable measurement of the blade 162 with respect to multiple dimensional coordinates and axes. In the illustrated embodiment, the blade sensor 210 can be disposed on the rear support bracket 180 mounted to the rear of the blade 162, and, in a more particular embodiment, may be located on the laterally arranged blade extension cylinder 202 at a location proximate with one or more hose couplings 212 connected to hoses from the hydraulic system. The blade sensor 210 may be adjacent to the bracket post 208 connected to the pitch cylinder 204 and may be located in between the first and second connecting arms 158 connecting the blade unit 160 to the circle assembly 150. The location of the blade sensor 210 at the rear of the blade unit 160 and below the upper free edge 168 of the blade 162 may protect the blade sensor 210 during operation of the motor grader 100. The curved front face 164 of the blade 162 will move material longitudinally forward and laterally toward the sides so that little or no material may rise up and over the upper free edge 168 of the blade 162 and encounter the blade sensor 210.

In an embodiment, to provide additional protection, the blade sensor 210 may be accommodated in a protective cover 214. Referring to FIG. 4, the protective cover 214 can be made from any suitable material such as impact resistant plastic or metal and can be formed as a hollow box 216, which may have a rectangular or other suitable shape, and which defines an interior 218 to receive the blade sensor 210. While FIG. 4 illustrates that the interior 218 may be accessible through an opening for installing the blade sensor 210, it will be appreciated that after installation, the opening may be enclosed with another component of the protective cover 214. In addition to protecting the blade sensor 210, the protective cover 214 may facilitate attachment of the blade sensor 210 to the location at the rear of the moldboard assembly 102. For example, the protective cover 214 may be configured to mount to the top of the blade extension cylinder 202 proximate to the hose couplings 212 via fasteners, mounting clips, welding, or the like. In an embodiment, because of the presence of the hose couplings 212, an existing channel or cavity 222 may be disposed in the exterior of the blade extension cylinder 202 or elsewhere on the rear support bracket 180 to accommodate and direct hydraulic hoses to the hose couplings 212. The cavity 222 therefore may provide additional protection for the blade sensor 210.

Furthermore, referring to FIGS. 2 and 3, the location of the blade sensor 210 may correspond approximately to the midpoint position 178 of the blade 162. The blade sensor 210 further may be spaced above the lower cutting edge 166 of the blade 162 and above the pivot joints 182 connecting the connecting arms 158 to the rear support bracket 180. The location of the blade sensor 210 as mounted to the moldboard assembly 102 enables it to directly measure at least two variables or coordinates representing the position or spatial orientation of the blade sensor 210 with respect to a coordinate system, such as one including the longitudinal axis 112, lateral axis 114, and vertical axis 116. For example, the blade sensor 210 can measure the pitch or orientation of the blade tip of the blade 162 including the amount the upper free edge 168 has been articulated longitudinally forward or aft of the lower cutting edge 166. In particular, extension or retraction of the pitch cylinder 204 can articulate the moldboard assembly 102 about the pivot joints 182. Because the blade sensor 210 is mounted directly on the moldboard assembly 102, it will articulate with the moldboard assembly 102 upon actuation of the pitch cylinder 204. Moreover, because the blade sensor 210 is vertically spaced above the pivot joints 182, articulation of the moldboard assembly 102 results in measurable curvilinear motion of the blade sensor 210. Through kinematic calculations and predetermined dimensional data about the moldboard assembly 102, the measured curvilinear motion of the blade sensor 210 can be used to determine the position of the upper free edge 168 with respect to the lower cutting edge 166, and thus the pitch of the blade 162 and the angle of the cut can be known. Because the blade sensor 210 is disposed on the moldboard assembly 102, it attains a direct measurement of the pitch of the blade 162.

The location of the blade sensor 210 also enables measuring the cross-slope orientation of the moldboard assembly 102 with respect to the ground 104. Because the blade sensor 210 is located approximately at the midpoint position 178 of the blade 162, the blade sensor 210 is located approximately at the center of relative displacement of the first and second blade sides 170, 172. Changing the cross-slope through relative vertical displacement of the first and second blade sides 170, 172 by independent actuation of the respective first and second lift cylinders 190, 192 may horizontally tilt the blade sensor 210 with respect to the lateral axis 114. The degree or measurement of the tilt of the blade sensor 210 can be computed to determine cross-slope of the moldboard assembly 102 with respect to the ground 104. Because the blade sensor 210 is mounted directly to the moldboard assembly 102, it directly measures vertical tilting of the moldboard assembly 102 with respect to the rest of the DCM assembly 140 and thus directly determines the cross-slope of the blade 162.

The blade sensor 210 can be any suitable type of dynamic sensor for measuring rotation and spatial orientation with respect to one or more coordinates. The blade sensor 210 is a type of dynamic sensor. Dynamic sensors may measure the movement of the object, and the measurements can be processed using kinematic equations and algorithms that convert measurable motions in terms like velocity, acceleration and rotation to determine and adjust position and/or orientation. The kinematic equations may be processed by the dynamic sensor, by a controller 139 in communication with the dynamic sensor, or the task may be divided between the two. For example, the blade sensor 210 can be an inertial measurement unit (IMU) which can measure linear and/or angular displacement with respect to one or more axes. An IMU may include accelerometers detecting linear acceleration and gyroscopes detecting rotational motion or rate. An IMU may be able to sense motion in relation to the x-y-z axes of a coordinate system and may measure rotation about any particular axis to provide pitch-yaw-roll. The x-y-z coordinates measured by an IMU may correspond to the longitudinal axis 112, lateral axis 114, and vertical axis 116. Examples of other sensors that may be employed as the blade sensor 210 include electromagnetic actuators, ultrasonic sensors, laser range sensors, potentiometers, limit switches, and the like.

In addition to the blade sensor 210, the motor grader 100 may include other sensors to assist in determining and adjusting the position of the moldboard assembly 102. For example, referring to FIG. 1, to determine the angular rotation of the circle 154 in relation to the journal disk 156 when swiveling the moldboard assembly 102 with respect to the rotational axis line 152, a rotational sensor 230 may be disposed at an appropriate location on the circle assembly 150. To determine the extension or retraction of the first and second lift cylinders 190, 192, which may correspond to the elevation of the moldboard assembly 102 with respect to the vertical axis 116, a lift sensor 232 may be operatively associated with the first and second lift cylinders 190, 192. To determine the orientation of the motor grader 100 with respect to the ground 104, for example, when the motor grader 100 is inclined or operating on a grade, a frame sensor 234 may be disposed on an appropriate location of the main frame 110.

To determine, more broadly, the location of the motor grader 100 with respect to a worksite, the motor grader 100 may be operatively equipped with a Global Positional Satellite (GPS) receiver 240. In a GPS system, the GPS receiver 240 receives coordinate signals from a plurality of orbiting satellites. The GPS receiver 240 can process the coordinate and timing information encoded in the coordinate signals and, by triangulating signals from different satellites, can accurately determine the geographic position of the GPS receiver 240 with respect to various locations on earth, such as a worksite. In the embodiment of the motor grader 100 illustrated in FIG. 1, the GPS receiver 240 may be mounted by a mast 242 to the moldboard assembly 102. The coordinate information received by the GPS receiver 240 is therefore particularly associated with the position and spatial orientation of the moldboard assembly 102 and, using that information in conjunction with machine dimensional information, can be processed to accurately determine to position and orientation of the blade 162 with respect to the ground 104.

INDUSTRIAL APPLICABILITY

To facilitate operation of the motor grader 100, the blade sensor 210 and other sensors may be in electronic communication with the controller 139 to send and receive digital or analog signals regarding their measurements. With reference to FIG. 5 in conjunction with FIGS. 1-4, the blade sensor 210 because of its location on the moldboard assembly 102 proximate the midpoint position 178 of the blade 162, may register the pitch of the blade 162 representing the position of the upper free edge 168 fore or aft of the lower cutting edge 166. The blade sensor 210 may generate a first signal 250 indicative of the pitch and communicate the first signal 250 to the controller 139. The blade sensor 210 may also register the cross-slope of the blade 162 with respect to the ground 104 in terms of the relative vertical heights of the first blade side 170 and second blade side 172. The blade sensor 210 may generate and communicate a second signal 252 indicative of the cross-slope to the controller 139.

As indicated above, the controller 139 may be adapted to process various kinematic algorithms and routines using the informational signals received from the sensors to assist controlling the motor grader 100. An example of such a process to control the position of the moldboard assembly 102 is illustrated in FIG. 5. After receiving the first signal 250 indicative of blade pitch and the second signal 252 indicative of cross-slope, the controller 139 may compare that information with respect to a desired worksite surface map 254, which may be a digital map of the desired worksite upon completion of grading, in a comparison step 256. If the controller 139 determines there is a variance between the information represented by the first and second signals 250, 252 and the desired worksite surface map 254, which may be caused by incorrect pitch angles or an incorrect cross-slope of the blade 162, the controller 139 can generate a corrective signal 258 representing corrective action to take. The controller 139 can send the corrective signal 258 to either the pitch cylinder 204, the first and second lift cylinders 190, 192, or both to selectively actuate them in accordance with the determined corrective action.

In another embodiment, the controller 139 can use the information provided by the blade sensor 210 regarding pitch and cross-slope of the blade 162 to adjust location data provided by the GPS receiver 240. For example, because the GPS receiver 240 is directly disposed on or connected to the moldboard assembly 102, movement of the moldboard assembly 102 results in movement of the GPS receiver 240. For example, if the blade 162 is pitched forward, the height of the GPS receiver 240 at the top of the mast 242 will change relative to the main frame 110 of the motor grader 100. However, using the first signal 250 and the second signal 252 provided by the blade sensor 210 and dimensional data about the motor grader 100, the controller 139 can compensate for movement of the GPS receiver 240 due to re-positioning of the moldboard assembly 102. The controller 139 therefore provides consistent positional information regarding the motor grader 100 and can calculate the precise orientation of the blade 162 with respect to the ground 104.

It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context. 

We claim:
 1. A motor grader comprising: a main frame defining a longitudinal axis; a moldboard assembly arranged generally traverse to the longitudinal axis, the moldboard assembly including a blade having an upper free edge, a lower cutting edge, a first blade side, and a second blade side, wherein the moldboard is movably connected to the main frame to: pivot the blade by moving the upper free edge with respect to the lower cutting edge; and slope the blade by vertically moving the first blade side with respect to the second blade side; a blade sensor disposed on and movable with the moldboard assembly, the blade sensor adapted to measure pitch of the blade and cross-slope of the blade.
 2. The motor grader of claim 1 wherein the moldboard assembly is part of a drawbar-circle-moldboard (DCM) assembly including: a drawbar coupled to the main frame by a universal joint; a circle assembly including a circle adapted to rotate with respect to the drawbar; and the moldboard assembly, the moldboard assembly being pivotally connected to the circle assembly.
 3. The motor grader of claim 2, wherein the blade includes a curved front face and a rear support bracket, the blade sensor disposed on the rear support bracket.
 4. The motor grader of claim 3, wherein the moldboard assembly further comprises a hydraulic actuator is accommodated on the rear support bracket and the blade sensor is disposed on the hydraulic actuator proximate a hose coupling.
 5. The motor grader of claim 3, wherein the moldboard assembly further includes protective cover mountable to the rear support bracket for protectively accommodating the blade sensor.
 6. The motor grader of claim 3, wherein the DCM assembly further a pitch cylinder disposed between the moldboard assembly and the circle assembly, the pitch cylinder configured to extend and retract to pivot the moldboard assembly with respect to circle assembly.
 7. The motor grader of claim 6, wherein the moldboard assembly is pivotally connected to the circle assembly by a plurality of connecting arms.
 8. The motor grader of claim 7, wherein the plurality of connecting arms are joined to the rear support bracket by pivot joints proximate to the lower cutting edge.
 9. The motor grader of claim 8, wherein the blade sensor is disposed on the rear support bracket proximate to the pitch cylinder.
 10. The motor grader of claim 2, further comprising a first lift cylinder and a second lift cylinder, the first lifter cylinder and the second lift cylinder being independently actuated to vertically move the first blade side with respect to the second blade side.
 11. The motor grader of claim 2, wherein the moldboard assembly and the blade sensor are disposed vertically below the circle assembly.
 12. The motor grader of claim 1, wherein the blade sensor is a dynamic sensor.
 13. The motor grader of claim 1, wherein the blade sensor is an inertial measurement unit including one or more gyroscopes and one or more accelerometers.
 14. The motor grader of claim 1, further comprising a GPS receiver mounted to the moldboard assembly.
 15. A motor grader comprising: a main frame defining a longitudinal axis; a moldboard assembly including a blade and movably connected to the main frame, the moldboard assembly adapted to move with respect to the main frame in a first dimension associated with a vertical axis perpendicular to the longitudinal axis and to move with respect to the frame in a second dimension associated with a lateral axis traverse to the longitudinal axis; and a blade sensor mounted to the moldboard assembly, the blade sensor adapted to directly measure movement of the moldboard assembly in the first dimension and in the second dimension.
 16. The motor grader of claim 15, wherein the blade includes a lower cutting edge, an upper free edge, a first blade side and a second blade side; and wherein movement of the moldboard assembly in the first dimension corresponds to moving the upper free edge with respect to the lower cutting edge; and movement of the moldboard assembly in the second dimension corresponds to moving the first blade side with respect to the second blade side.
 17. A control system for a motor grader comprising: a drawbar-moldboard-circle (DCM) assembly including a drawbar movably connected to a frame of the motor grader, a circle assembly rotatably connected to the drawbar, and a moldboard assembly pivotally connected to the circle assembly; a blade sensor disposed on a moldboard assembly of the motor grader, the blade sensor configured to measure pitch and cross-slope of the moldboard assembly; and a controller in communication with the blade sensor to receive from the blade sensor a first signal indicative of pitch of the moldboard assembly and a second signal indicative of the cross-slope of the moldboard assembly, the controller further configured to process the first signal and the second signal to generate one or more control signals to control positioning of the moldboard assembly.
 18. The control system of claim 17, wherein the moldboard assembly includes a blade having a lower cutting edge, an upper free edge, a first blade side and a second blade side.
 19. The control system of claim 18, wherein the first signal indicative of pitch indicates relative position of the lower cutting edge and upper free edge, and the second signal indicative of cross-slope indicates relative position of the first blade side and the second blade side.
 20. The control system of claim 19, wherein the controller communicates the one or more control signals to one or more actuators operatively connected to the DCM assembly to position the moldboard assembly. 